Cheryl Cole is evidently not the only one concerned with retrieving her hair's mojo. In Britain we spend £800m a year on haircare products, £120m on dyes and £65m on extensions. This all leaves a big eco footprint. The largest carbon impact is in washing your hair, specifically heating hot water.

Many worry about the variety of synthetic chemicals in hair products. There are strong eco-alternative brands: Green People, Bulldog for men (Fairtrade), and Intelligent Nutrients (an eco hairspray that works). But terms such as "natural" are unregulated, and some brands make dubious substitutions.

Paraphenylenediamine (PPD), found in more than two-thirds of hair dyes because it covers up grey, can trigger devastating allergic reactions. If you go to a salon, visit one that minimises PPD concentrations, such as Karine Jackson in London. Beauty is full of injustice: half of British hairdressers are now suffering from a form of dermatitis, and salon chemical exposure is linked to bladder cancer.

Hair from the salon floor is thrown into landfill – and then, bizarrely, we import new hair. Investigations have traced human hair extensions back to Russian prisoners, women in asylums, and temple sacrifices where women have not received any direct income. Hair-raising, to say the least.